Overrunning decouplers for serpentine drives and the like on internal combustion engines are well known and operate to reduce torsional vibrations in the serpentine drive which are created by combustion strokes of the engine and intermittent loads on the serpentine belt.
Such decouplers typically include a one way clutch, which operate such that the decoupler only transmits torque in one rotational direction, and an isolation spring which operates between the decoupler pulley and the accessory device driven by the pulley to dampen the torsional vibrations.
Typically, such overrunning accessory decouplers (OAD's) are installed on the alternator of an internal combustion engine, as the alternator has the highest inertial load of the accessories driven by the serpentine drive.
By employing an OAD on a serpentine drive, numerous advantages can be obtained, including increasing the life of the serpentine belt, decreasing the spring force requirements of the belt tensioner for the serpentine system, etc.
Examples of OAD's include published PCT application WO 2004/011818, published PCT application WO 98/50709, U.S. Pat. Nos. 5,156,573 and 6,044,943 amongst several others.
Recently, interest has been expressed in employing an alternator, or generator, as a starter to replace the need for a conventional starter motor or to employ the alternator/generator as a starter assist device, allowing a starter motor to be employed which has a smaller output capacity than would otherwise be required, the smaller starter and the alternator/generator starter assist device operating in combination.
While known OAD's do improve serpentine drives, they do suffer from a disadvantage in that they only transmit torque in one direction, namely from the driving serpentine belt to the accessory, thus preventing their use with alternator/generator starters or starter assist devices.
It is desired to have an OAD that can be used with an alternator/generator starter or starter assist device.